1. Chapter 10: Lesson 4: Solving Percent Problems with Proportions
Objective:
Learn to use proportions to solve percent problems.

2. Another way to solve percent problems is by using proportions.
Steps:
First re-write percents as fractions by writing them over a 100.
Then use the information in the problem to write the other ratio.
Multiply to find the cross products.
Use the inverse operation.
Solve for the variable.
P = is of

3. Example 1: What number is 47% of 280? 100 of 47 = N 100 280
p = is of
47 = N
100N = 47 × 280
100N = 13,160
N =

4. Example 2: P = is 38 = 52 52 is 38% of what number? 100 of 100 N
38 = 52 N
38 N = 5200
N =

5. Example 3: 45 is what percent of 90? P = 45 100 90 100 90
90P = 45 x 100
90P =
P = %

6. Homework: Use proportions to solve percent exercises.
What number is 70% of 45?
15 is 25% of what number?
What number is 75% of 125?
7 is what percent of 77?
What number is 23% of 75?